The present invention relates generally to the field of articulated bed and seat forming frame structures.
It has heretofore been generally known from a number of commercially available convertible sofa-bed structures to provide an interconnected seat frame and back frame which can be manually operated to effect a seat forming position and/or a bed forming position, and in which the translatory movements of the seat and back frames in going from one of these positions to the other, is controlled by an articulated linkage mechanism which may vary widely as to construction, design and complexity.
U.S. Pat. No. 3,657,747 is illustrative, and discloses a sofa-bed arrangement in which seat and backrest sections are supported relative to a base structure by a linkage mechanism which includes front and rear swing arms both of which are pivotally mounted to the base at their lower ends with the front swing arm being pivotally connected at its upper end to the seat section. The upper end of the rear swing arm is pivotally connected to a carrier link, one end of which is pivotally connected to the back-rest section with an intermediate portion thereof being pivoted to an intermediate portion of the front swing arm. The forward extremity of the carrier link is pivotally connected to an actuating link which in turn is pivotally connected to a support leg for the seat section to move the support leg between extended and retracted positions when the sofa-bed is moved between the bed and sofa positions. In this disclosed arrangement, a tension spring is provided to bias the sofa-bed in both of the sofa and bed positions and also to assist in moving it to either position.
The known arrangements have in general operated more or less satisfactorily to accomplish the conversion from a sofa to a bed, and vice versa. However, these arrangements have not in general been all that might be desired in this type of structure. The linkage mechanism is usually relatively complex and expensive, and the mechanical design is such that in some arrangements considerable manual effort is required to convert the sofa-bed from one position to the other, despite the use of assisting loading springs.
The present invention seeks to overcome the inherent disadvantages of the presently known structures by providing a novel and unique articulated control linkage in which the seat and back sections are hingedly interconnected, and are supported by a front link having one end pivoted on a base structure and another end pivoted on the seat, a rear link member having one end pivoted on the base structure and another end pivoted on the back, while an intermediate control member in the form of a bracket is slidably supported for movement on a base rail between the back and front of the base structure, the bracket having an upstanding portion pivotally connected to the back adjacent the hinged interconnection with the seat. This constitutes a greatly simplified linkage mechanism, and one which permits conversion from one position to the other with surprising ease of operation.